In Star Wars: A New Hope Princess Leia utters the famous plea, “Help me, Obi-Wan Kenobi. You’re my only hope.” Carl Sagan, in a short course I took from him at the University of Toronto, asserted that mankind’s only hope for survival was to get counsel from an extraterrestrial intelligent civilization, specifically from such a civilization’s “Encyclopedia Galactica.”
Long before the Star Wars movies, a few astronomers used some of the world’s largest telescopes to search for signals sent out by extraterrestrial intelligent civilizations. Such efforts failed. These failures, however, have done little to blunt the enthusiasm for finding extraterrestrial intelligence. The SETI (Search for Extraterrestrial Intelligence) Institute was founded in 1984. Thanks to generous donations from Microsoft co-founder Paul Allen, the Allen Telescope Array (with its 42 antennas) has been built and dedicated to SETI observations.
Recently, astronomers have adopted a new approach to finding intelligent civilizations. Rather than looking for communication signals that may or may not be aimed at us, astronomers are attempting to detect the energy processing activities of such civilizations. This approach is based on the correlation between a civilization’s level of technological advancement with the amount of energy such a civilization needs to consume to maintain such technological capability.
Russian astronomer Nikolai Kardashev defined three categories of advanced civilizations:1
- Kardashev I: a civilization harnessing a large fraction of its planet’s incident radiation and stores of energy
- Kardashev II: a civilization harnessing a large fraction of its host star’s energy output
- Kardashev III: a civilization harnessing a significant fraction of the energy output from its galaxy’s stars
American physicist Freeman Dyson explained how an intelligent civilization would proceed to harvest the energy output of a star.2 Similar to putting solar panels on a roof, a civilization could surround its star or other stars with energy-capturing structures. Such structures have been labeled Dyson spheres.
Whereas previous generations of astronomers lacked the telescope power to detect Dyson spheres, today’s researchers possess that capability. In an Astrophysical Journal paper, four Swedish astronomers noted that Dyson spheres surrounding a large number of stars in a galaxy would change both the apparent luminosity and color of those stars as seen from Earth without changing the galaxy’s gravitational potential.3The team proceeded to search for those changes in the latest galaxy survey databases. In a sample of 1,359 spiral galaxies (only spiral galaxies are candidates for hosting advanced life4) the team failed to detect the existence of a Kardashev III level civilization.
For Stars Wars fans this failure means that galaxy-wide conflicts remain in the realm of fantasy.
Members of a team of 29 American and European astronomers now speculate that they might have found a Kardashev II civilization. The entire team has submitted a paper to the Monthly Notices of the Royal Astronomical Society where they reported on an observed anomalous dimming of the star KIC 8462852.5
The dimming is not characteristic of a transiting planet or brown dwarf. It is irregular. In their paper the team considered seven possible explanations for the dimming:
- Instrumental effects or data reduction artifacts
- Intrinsic variability in the star’s light output
- Variability of KIC 8462852’s companion star
- Variability in light absorption by dust clouds and clumps surrounding the star
- Aftermath of catastrophic collisions in an asteroid belt
- Aftermath of a giant impact in the planetary system
- Breakup of one or more large comet bodies that resulted in a cloud of disintegrating comets
Observations of the star and planet formation models eliminated all but the last explanation. In their summary the team concluded that a comet swarm was the most likely answer to the observed dimming.
After submitting the paper, the lead author, Tabetha Boyajian, speculated that the dimming might be caused by a Kardashev II civilization. Several interviews and Internet articles later, Boyajian and two of her colleagues garnered two weeks of time to observe on the Allen Telescope Array hoping to catch some communication signals from the possible civilization in the possible KIC 8462852 system. Alas, they found none.
There was no need to expend the telescope time since KIC 8462852’s characteristics rule out the possibility that it could host a planet on which intelligent life exists. The spectral type of KIC 8462852 is F3V/IV, contrasted with the Sun’s G2V. F3V/IV stars are nearly five times more luminous than the Sun. They burn through their nuclear fuel much more rapidly, emit much more deadly ultraviolet radiation, and manifest much more flaring activity. Any one of these distinct features would eliminate the possibility that a planet orbiting KIC 8462852 could sustain life long enough to provide the environmental conditions and biodeposits needed for an intelligent species.
KIC 8462852’s rotation period is only 0.88 days, about 30 times more rapid than the Sun’s. Rapid stellar rotation is strongly correlated with high flaring activity, much too high for the survival of terrestrial animals. Also, rapid stellar rotation usually implies a stellar age much too young for the long life history an entrance of intelligent life would require.
Spectral measurements of KIC 8462852’s light output reveal no significant infrared excess. The lack of excess infrared radiation contradicts the hypothesis that an intelligent civilization is using a Dyson sphere on KIC 8462852 to harvest energy. Such harvesting would involve the capturing of the star’s ultraviolet and visible light to generate electricity or other forms of useful energy and the dissipation of heat (infrared radiation) resulting from such exploitation. KIC 8462852 is neither anomalously dim at ultraviolet and visible wavelengths nor is it anomalously bright at infrared wavelengths.
Though, in many respects SETI research is futile, these latest SETI efforts are yielding greater insights and appreciation for just how much planning and preparation are needed to make possible a narrow time window during which intelligent life can exist—not to mention launch and sustain a high-technology civilization. No such species and civilization is possible apart from the handiwork of a super-intelligent, super-powerful, super-benevolent Creator. If there is intelligent life elsewhere in the universe, it exists thanks to the miraculous interventions of that Creator.
So far, everywhere beyond Earth that astronomers look only reveals environments extremely hostile to advanced life. Where, then, can we find the hope Sagan longed for? We already have an "Encyclopedia Galactica," namely, the Bible itself. In it we find that our only hope is to get counsel and deliverance from God, the Creator and Redeemer.